The Gentleman is always truthful and sincere; will not agree for the sake of complaisance or out of weakness ; will not pass over that of which he disapproves. He has a clear soul, and a fearless, straightforward tongue. On the other hand he is not blunt and rude. His truth is courteous; his courtesy, truthful; never a humbug, yet, where he truthfully can, he prefers to say pleasant things. [J.R. Vernon, "Contemporary Review," 1869]

Related: Gentlemen. Gentleman's agreement is first attested 1929. Gentleman farmer recorded from 1749.